nick@nick-burst:~$ sudo dpkg --configure -a
[sudo] password for nick:
Setting up linux-image-4.15.0-50-generic (4.15.0-50.54) ...
Setting up grub-efi-amd64-signed (1.93.14+2.02-2ubuntu8.13) ...
Installing for x86_64-efi platform.
grub-install: error: efibootmgr failed to register the boot entry: Unknown error -1.
dpkg: error processing package grub-efi-amd64-signed (--configure):
 installed grub-efi-amd64-signed package post-installation script subprocess returned error exit status 1
Processing triggers for linux-image-4.15.0-50-generic (4.15.0-50.54) ...
/etc/kernel/postinst.d/initramfs-tools:
update-initramfs: Generating /boot/initrd.img-4.15.0-50-generic
/etc/kernel/postinst.d/zz-update-grub:
Sourcing file `/etc/default/grub'
Generating grub configuration file ...
Found linux image: /boot/vmlinuz-4.15.0-50-generic
Found initrd image: /boot/initrd.img-4.15.0-50-generic
Found linux image: /boot/vmlinuz-4.15.0-44-generic
Found initrd image: /boot/initrd.img-4.15.0-44-generic
Found linux image: /boot/vmlinuz-4.15.0-43-generic
Found initrd image: /boot/initrd.img-4.15.0-43-generic
Found Windows Boot Manager on /dev/mmcblk1p1@/efi/Microsoft/Boot/bootmgfw.efi